This invention relates generally to integrated gasification combined-cycle (IGCC) power generation systems, and more specifically to methods and apparatus for reducing the quantity of solids carried over from the gasifiers into the high temperature syngas coolers that may be employed in IGCC systems where ash-containing fuels are fed to the gasifiers.
At least some known gasification systems include a reaction chamber that forces any particles in the product syngas (unconverted fuel, soot and/or ash in the form of molten slag) to exit the reactor along with all of the gas. Entrainment of all the particles in the product syngas, particularly in the case where a syngas cooler is used immediately downstream of the reactor to cool the gas and particles, results in much more difficult design requirements for the syngas cooler. The syngas cooler must be designed to minimize solids deposition on the heat exchange surfaces so that the cooler can operate with minimal risk of becoming plugged with solids. Such syngas cooler designs require substantial space, both vertically and radially, to enable them to adequately cool both the syngas and the entrained particles. Known syngas cooler designs, which may be oriented in a vertical down-flow configuration below the gasifier, have typically provided a large diameter open channel disposed about the long flow axis of the cooler to allow the passage of solids through the cooler along the centerline without contacting the peripheral heat exchange surfaces. Such syngas cooler designs are large, expensive to manufacture and require expensive support structures.